Apparatus and method for determining soft or softer handoff in mobile communication system

Abstract

Apparatus and method for determining soft or softer handoff are described. The present invention includes the steps of comparing sectors in an active set to set values corresponding to the soft or softer handoff for the sectors, respectively in a base station, transmitting a first parameter for selecting cell switching parameters between the sectors neighboring each other in the active set to a mobile station wherein the set values for the respective sectors are included in the first parameter, generating values of a parameter PDCH_GROUP_IDENTIFIER corresponding to a packet data channel group identifier using the set values included in the first parameter, determining whether a serving sector and a target sector among the sectors are in the soft or softer handoff using the generated values of the parameter PDCH_GROUP_IDENTIFIER, and selecting the cell switching parameters accordingly.

1. A method of cell switching in a mobile communication system comprising at least one base station, each base station corresponding to one-or-more sectors, comprising the steps of:
 determining an active set comprising at least one sector being a serving sector; 
 receiving a control parameter for each sector in the active set, the control parameter being associated with using at least one of first-type and second-type handoff when transitioning from the serving sector to a target sector; 
 determining identifier parameters corresponding to the sectors in the active set, each identifier parameter being determined by associating control parameters of at least two sectors in the active set, wherein the identifier parameters are determined by comparing the control parameter of one sector to next sector in the active set so that if the control parameter of the next sector is at a first logic level, then the corresponding identifier parameter is set to previous identifier parameter, and if the control parameter of the next sector is at a second logic level, then the corresponding identifier parameter is increased by a predetermined value from the previous identifier parameter; 
 determining at least one of the first-type and the second-type handoff by comparing at least two identifier parameters corresponding to the sectors in the active set; and 
 selecting cell switching parameters corresponding to at least one of the first-type and the second-type handoff. 
 
   
   
     2. The method of  claim 1 , wherein the control parameters is determined by using one sector of the active set as a reference and comparing other sector in the active set to determine whether neighboring sectors are with the same cell, wherein a cell comprises at least one sector. 
   
   
     3. The method of  claim 1 , wherein if a packet data channel group indicator is received from the network, the control parameter comprises the packet data channel group indicator, otherwise, the control parameter comprises a power combining indicator. 
   
   
     4. The method of  claim 1 , wherein the identifier parameter corresponding to a first sector in the active set is set to a predetermined value. 
   
   
     5. The method of  claim 1 , wherein the step of determining the identifier parameters further comprises:
 setting a next identifier parameter to the identifier parameter of previous sector in the active set that supports the packet data communication, if corresponding control parameter is set to a first level and there are no other sectors between a present sector corresponding to the next identifier parameter and a previous sector that support the packet data communication; 
 setting the identifier parameter to the identifier parameter of previous sector in the active set that supports the packet data communication, if corresponding control parameter is set to a first level and all sectors between the present sector corresponding to the next identifier parameter and a previous sector in the active set that support packet data communication have corresponding control parameter set to the first level; and 
 otherwise set the identifier parameter to a value different than the identifier parameter corresponding to previous sector that supports the data packet communication in the active set. 
 
   
   
     6. The method of  claim 5 , further comprising: setting the identifier parameter corresponding to a first sector in the active set to a predetermined value. 
   
   
     7. The method of  claim 1 , wherein the step of determining the first-type and second-type handoff further comprises:
 comparing the identifier parameter of the serving sector to the target sector in the active set so that if both identifier parameters are different then the first-type handoff is recognized for the mobile terminal to transition from the serving sector to the target sector, and 
 if both identifier parameters are the same, then the second-type handoff is recognized. 
 
   
   
     8. The method of  claim 5 , wherein the step of determining the first-type and second-type handoff further comprises:
 comparing the identifier parameter of the serving sector to the target sector in the active set so that if both identifier parameters are different then the first-type handoff is recognized for the mobile terminal to transition from the serving sector to the target sector, and 
 if both identifier parameters are the same, then the second-type handoff is recognized. 
 
   
   
     9. A mobile station for use in a mobile communication system comprising at least one base station, each base station corresponding to one-or-more sectors, the mobile station comprising:
 an antenna; 
 a processor for controlling the mobile station; 
 a display in communication with the processor to display user interface information; 
 a keyboard in communication with the processor to input user controlled data; 
 the processor comprising
 means for receiving a control parameter for each sector in the active set, the control parameter being associated with using at least one of first-type and second-type handoff when transitioning from the serving sector to a target sector; 
 means for determining identifier parameters corresponding to the sectors in the active set, each identifier parameter being determined by associating control parameters of at least two sectors in the active set, wherein the identifier parameters are determined by comparing the control parameter of one sector to next sector in the active set so that if the control parameter of the next sector is at a first logic level, then the corresponding identifier parameter is set to previous identifier parameter, and if the control parameter of the next sector is at a second logic level, then the corresponding identifier parameter is increased by a predetermined value from the previous identifier parameter; 
 means for determining at least one of the first-type and the second-type handoff by comparing at least two identifier parameters corresponding to the sectors in the active set; and 
 means for selecting cell switching parameters corresponding to at least one of the first-type and the second-type handoff. 
 
 
   
   
     10. The mobile station of  claim 9 , wherein the control parameters is determined by using one sector of the active set as a reference and comparing other sector in the active set to determine whether neighboring sectors are with the same cell, wherein a cell comprises at least one sector. 
   
   
     11. The mobile station of  claim 9 , wherein if a packet data channel group indicator is received from the network, the control parameter comprises the packet data channel group indicator, otherwise, the control parameter comprises a power combining indicator. 
   
   
     12. The mobile station of  claim 9 , wherein the identifier parameter corresponding to a first sector in the active set is set to a predetermined value. 
   
   
     13. The mobile station of  claim 9 , wherein the processor determines the identifier parameters by:
 setting a next identifier parameter to the identifier parameter of previous sector in the active set that supports the packet data communication, if corresponding control parameter is set to a first level and there are no other sectors between a present sector corresponding to the next identifier parameter and a previous sector that support the packet data communication; 
 setting the identifier parameter to the identifier parameter of previous sector in the active set that supports the packet data communication, if corresponding control parameter is set to a first level and all sectors between the present sector corresponding to the next identifier parameter and a previous sector in the active set that support packet data communication have corresponding control parameter set to the first level; and 
 otherwise set the identifier parameter to a value different than the identifier parameter corresponding to previous sector that supports the data packet communication in the active set. 
 
   
   
     14. The mobile station of  claim 13 , further comprising: setting an identifier parameter corresponding to a first sector in the active set to a predetermined value. 
   
   
     15. The mobile station of  claim 9 , wherein the step of determining the first-type and second-type handoff further comprises:
 comparing the identifier parameter of the serving sector to the target sector in the active set so that if both identifier parameters are different then the first-type handoff is recognized for the mobile terminal to transition from the serving sector to the target sector, and 
 if both identifier parameters are the same, then the second-type handoff is recognized. 
 
   
   
     16. A method of cell switching using an active set of sectors in a mobile communication system comprising at least one fixed station, each fixed station corresponding to one-or-more sectors, comprising the steps of:
 receiving a control parameter for each sector in the active set, the control parameter being associated with using at least one of first-type and second-type handoff when transitioning from a serving sector to a target sector; 
 determining identifier parameters corresponding to the sectors in the active set, each identifier parameter being determined by associating control parameters of at least two sectors in the active set, wherein the identifier parameters are determined by comparing the control parameter of one sector to next sector in the active set so that if the control parameter of the next sector is at a first logic level, then the corresponding identifier parameter is set to previous identifier parameter; 
 determining at least one of the first and the second handoff by comparing at least two identifier parameters corresponding to the sectors in the active set; and 
 selecting cell switching parameters corresponding to at least one of the first and the second handoff. 
 
   
   
     17. The method of  claim 16 , wherein the control parameters is determined by using one sector of the active set as a reference and comparing other sector in the active set to determine whether neighboring sectors are with the same cell, wherein a cell comprises at least one sector. 
   
   
     18. The method of  claim 16 , wherein if a packet data channel group indicator is received from the network, the control parameter comprises the packet data channel group indicator, otherwise, the control parameter comprises a power combining indicator. 
   
   
     19. The method of  claim 16 , wherein the step of determining the identifier parameters further comprises:
 comparing the control parameter of one sector to next sector in the active set so that if the control parameter of the next sector is at a second logic level then the corresponding identifier parameter is increase by a predetermined value from the previous identifier parameter. 
 
   
   
     20. The method of  claim 16 , wherein the step of determining the identifier parameters further comprises:
 setting a next identifier parameter to the identifier parameter of previous sector in the active set that supports the packet data communication, if corresponding control parameter is set to a first level and there are no other sectors between a present sector corresponding to the next identifier parameter and a previous sector that support the packet data communication; 
 setting the identifier parameter to the identifier parameter of previous sector in the active set that supports the packet data communication, if corresponding control parameter is set to a first level and all sectors between the present sector corresponding to the next identifier parameter and a previous sector in the active set that support packet data communication have corresponding control parameter set to the first level; and 
 otherwise set the identifier parameter to a value different than the identifier parameter corresponding to previous sector that supports the data packet communication in the active set. 
 
   
   
     21. The method of  claim 20 , further comprising: setting the identifier parameter corresponding to a first sector in the active set to a predetermined value. 
   
   
     22. The method of  claim 16 , wherein the step of determining the first-type and second-type handoff further comprises:
 comparing the identifier parameter of the serving sector to the target sector in the active set and based on the comparison determining whether the first-type or second-type handoff is recognized.